A new study from Stanford University has shown that common mealworms can survive on a diet of Styrofoam and other types of polystyrene, potentially leading to new solutions to address the global plastic pollution problem.

The study, published in Environmental Science and Technology, says that the tiny worm, which is the larvae form of the darkling beetle, has microorganisms in its guts that can process plastic. The researchers made this “surprising” discovery after observing 100 mealworms in a laboratory, which ate between 34 and 39 milligrams of Styrofoam per day.

Within 24 hours, the worms converted about half of the Styrofoam into carbon dioxide while excreting the bulk of the remaining plastic as biodegraded fragments that looked like tiny rabbit droppings. The mealworms’ waste appeared to be safe to use as soil for crops, according to Wei-Min Wu, the study’s co-author and a senior research engineer in the Department of Civil and Environmental Engineering at Stanford.

This is not the first time that Wu and his colleagues have analysed worms which subsist on a plastic diet. In an earlier research, they found that waxworms, the larvae of Indian mealmoths, have microorganisms in their guts that can biodegrade polyethylene, a plastic used in filmy products such as trash bags.

However, the new research on mealworms is considered to be more significant because Styrofoam is believed to be non-biodegradable and more problematic for the environment.

To investigate this new discovery further, researchers led by Craig Criddle, a professor of civil and environmental engineering who supervises the plastics research at Stanford, are conducting ongoing studies with a team from the University in China. Together, they plan to study whether microorganisms within mealworms and other insects can biodegrade other plastics such as polypropylene, microbeads and bioplastics.

According to Criddle, another area of their research could involve searching for a marine equivalent of the mealworm to digest plastics. Plastic waste is a global concern in the ocean, as millions of tonnes of rubbish enter the world’s oceans each year. Almost 90 percent of the marine debris found on Sydney’s beaches alone is plastic, mostly bottles, caps and straws.

Around one million seabirds and 100,000 marine mammals worldwide are estimated to be killed every year by plastics, either by being entangled and strangled or choked and starved. Previous investigations have shown that marine life, such as seabirds and turtles, mistake larger pieces of plastic floating at the surface for food.

The researchers note that more studies are needed to understand the conditions favourable to plastic degradation and the enzymes that break down polymers. They say this could help scientists engineer more powerful enzymes for plastic degradation, as well as guide manufacturers in designing polymers that do not accumulate in the environment or in food chains.

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